从android发送文本和表情符号到PHP？

I tried to send text + emoji of android to another android throught php, in php I wrote the code to insert into mysql, everything work well but when it entered into table, the result change tobe question mark "??" I've tried to find tutorials about this but I cant try it in my application

I tried to send a text + emoji using json array.

I use this code in java to send to php

HttpClient client = new DefaultHttpClient();
HttpResponse response;
try{
    HttpPost post = new HttpPost(url);
    List<NameValuePair> nVP = new ArrayList<NameValuePair>(2);  
    nVP.add(new BasicNameValuePair("mydata", paketan.toString()));  //studentJson is the JSON input
    post.setEntity(new UrlEncodedFormEntity(nVP,"UTF-8"));
    response = client.execute(post);
    response.setHeader("Content-Type", "application/json; charset=utf-8");
    hsl = org.apache.http.util.EntityUtils.toString(response.getEntity());

this log in eclipse.

[{"Time": "2015-07-09 14:21:17", "msg": "test emoji